Phosphorus-containing carbamates

ABSTRACT

This invention relates to phosphorus-containing carbamates having at least one N-methylol or N-alkoxymethyl group. These compounds can be used to impart durable flame-retardant properties to cellulose-containing substrates.

United States Patent Gaj et al. 1 Sept. 11, 1973 PHOSPHORUS-CONTAINING 1,817,682 7/1970 Germany 260/938 CARBAMATES 963,631 7/1964 Great Britain 260/938 Inventors: Bernard J. Gaj, Montclair; Stephen B. Sello, Cedar Grove, both of NJ Assignee: J. P. Stevens & Co., Inc., New York,

Filed: June 18, 1971 Appl. No.: 154,690

US. Cl. 260/482 B, 117/136, 260/482 C, 260/938, 260/942, 260/952 Int.- Cl. C07c 125/06 Field of Search 260/482 B, 482 C, 260/938 References Cited FOREIGN PATENTS 0R APPLICATIONS 4/1965 Germany 260/938 OTHER PUBLICATIONS Journal Chemical Society, 1957, 1323-1329 Primary ExaminerLorraine A. Weinberger Assistant Examiner-Paul J. Killos Attorney-Michael T. Frimer and Charles Stein et a1.

[57] ABSTRACT This invention relates to phosphorus-containing carbamates having at least one N-methylol or N- alkoxymethyl group. These compounds can be used to impart durable flame-retardant properties to cellulosecontaining substrates.

3 Claims, No Drawings 1 PHOSPHORUS-CONTAINING CARBAMATES The present invention relates to novel phosphoruscontaining carbamates having at least one reactive N- methylol or N-alkoxymethyl group. Flame-retardant properties are imparted to cellulose-containing substrates by reacting the carbamate compounds with cellulosic hydroxyl groups.

The phosphorus-containing carbamates of this invention have the formula where I R is alkyl of one to five carbon atoms; a is an integer equal to 3-b; b is an integer of l to 3, and Z is a radical selected from the group consisting of CHaORa wherein I R is an alkylene radical of one to five carbon atoms; R, is hydrogen, alkyl of one to five carbon atoms or -CH,OR,; I R, is hydrogen or'alkyl of one to five carbon atoms,

and

wherein R,, R,, and R,have the meanings given above, and R is an alkylene radical of one to five carbon atoms. Carbamates of this invention can be prepared by reacting a phosphorus-containing alcohol of the formula where X is -R,0H or -R N(R,OH), and R and R, have the meanings given above, with an isocyanate of the formula OCNR,

where R is hydrogen or alkyl of one to five carbon atoms, in presence of a basic solvent such as pyridine whereby reaction takes place at the R,OH groups to give R,OCONHR, groups and then methylolating the resulting intermediate product by reaction with formaldehyde. This reaction is illustrated by the following equations in which the phosphorus-containing alcohol is tris-(hydroxymethyl) phosphine oxide and the isocyanate is methyl isocyanate.

pyridine 1| liGllzO {I 1(CH;OCONHCH3); CH OCON groups,

where R, is hydrogen or alkyl of one to five carbon atoms,

and then methylolating this intermediate with formaldehyde to obtain the desired phosphorus-containing carbamate. These reactions are illustrated by the following equations wherein the phosphorus-containing alcohol has the formula ca-1,0i,P 0)cH,N cH,cH,oH

and ammonia is used onion i onion 1 If the methylolation procedure of the two abovedescribed processes is carried out using a solution of formaldehyde in an alkanolsuch as methyl or ethyl alcohol and the product obtained is acidified e.g. with HCl, the carbamate produced has N-alkoxymethyl groups'in place of the N-hydroxyrnethyl groups shown in the above equations.

Representatives of the alcohols which are useful starting materials for the preparation of the phosphorus-containing carbamates of this invention are the following compounds:

(2) (CHrCHaO):PCH1N(CH:CH2OH)1 a (3) (CIIJCII10)QPCII1ON CHaCH101F CHgOHM (6) CHgCHzO P(CH2CH;OH)1

( 1|T(CH2OH2OH)3 The compoundsof this invention are useful as durable flame-retardant agents for cellulose-containing substrates. The N-hydroxymethyl or N-alkoxymethyl groups react with cellulosic hydroxyl groups forming water-insoluble cellulose ethers which contain both nitrogen and phosphorus. This reaction is carried out by heating at a temperature of about 60 to 200C, preferably at 120 to 180C., in the presence of an acidic catalyst.

Suitable acidic compounds for catalyzing the reaction of the carbamates of this invention with cellulosic hydroxyl groups include the ammonium or amine salts of mineral acids; the chlorides and nitrates of zinc and magnesium; acid fluoride salts; and zinc fluoroborate. In addition to the above salts, non-volatile acids of moderate strength such as citric acid and sodium hydrogen sulfate can also be employed. The amount of acidic catalyst added to the treating bath should be equal to about 0.2 to 10 percent by weight based on the weight of the treating bath, and preferably from 0.3 to 4.0 percent by weight.

The phosphorus-containing carbamate and the acidic catalyst can be applied from an aqueous solution or dis.- persion by padding, brushing, spraying, or other impregnation technique. It is preferable that after formation of the reaction product the add-on of bound phosphorus be about 0.5 to 4.0 weight based on the weight of the finished product, i.e., substrate plus flameretardant reaction product. The concentration of the carbamate reactant in the impregnation bath-and the wet pickup are adjusted to give the desired add-ons of phosphorus. The add-on of bound nitrogen also contributes to the flame-retardant properties of the treated substrate. The amount of nitrogen in the treated product can be increased by using one or more nitrogencontaining compounds in conjunction with the carbamates of the invention. The add-on of bound nitrogen should be about 1.0 to percent by weight based on the weight of the finished product.

The phosphorus-containing carbamates can be used in conjunction with a nitrogen-containing, durablepress resin such as N-hydroxymethyl or N- alkoxymethyl derivatives of non-phosphoruscontaining carbamates, dimethylol urea, dimethylol alkylene urea, dimethylol dihydroxy alkylene urea, polymethylol, uron, polymethylol melamines, etc. In such cases, a portion of the nitrogen required for flame retardancy can be supplied by the durable-press resin. The phosphorus-containing carbamate and the durable-press resin can be applied in a single step operation or by sequential treatments with either compound being applied first. The reaction of the durable-press resin with cellulose is catalyzed with the same type of acidic catalyst used with the phosphorus-containing carbamate.

If desired, polymethylol melamine resins can be employed using a wet fixation technique so that an insoluble nitrogen-containing product is formed on the substrate with little or no reaction with the cellulose. 1n the wet fixation procedure (e.g., steaming) the moisture content of the substrate is maintained at a minimum of 10 percent by weight based on the weight of the substrate during the reaction of the polymethylol melamine to form an insoluble product. When the phosphorus-containing carbamate and the polymethylol melamine are applied to a fabric simultaneously, it is preferable to first steam the fabric to self-polymerize the polymethylol melamine and then to dry heat the fabric in the presence of an acidic catalyst to react the carbamate with cellulosic hydroxyl groups.

The cellulosic substrate to be rendered flame retardant should contain at least 30 weight percent cellulose. The substrate can be a yarn or thread, or a woven, knitted or non-woven fabric.

Particularly outstanding compounds within the scope of the present invention which give excellent flameretardant properties are compounds of the formula where R R, and R have the meanings given above. Another preferred group of carbamate compounds within the scope of this invention has the formula where R,, R R and R have the meanings given above.

The following examples are given to further illustrate the invention, but it is to be understood that the invention is not to be limited in any way but by the details described therein. in the examples percents are by weights unless otherwise specified.

Analytical and Test Methods Employed in the Examples Bound Nitrogen, N in percent: Determined by Kjeldahl digestion, followed by titration of the distilled ammonia.

Bound Phosphorus, P in percent: Determined by Kjeldahl digestion, followed by colorimetric analysis employing acetone-water to intensify the phosphomolybdate color: Bernhart et al., Anal. Chem., Vol. 27, 440 (1955).

Flame Retardancy (Vertical Test), char length in inches: AATCC 34-1966. A char length of about 6 inches or shorter is passable.

Flame Retardancy (Limiting Oxygen Index), the minimum value of the volume fraction (expressed in decimal form) of oxygen in a metered oxygen-nitrogen mixture, using a flammability index tester (Type FL- 101, General Electric Co.): C.P. Fenimore and FJ. Martin, Combustion and Flame, Vol. 10, No. 2, (June 1966), and Modern Plastics, Vol.43, No. 11, 141 (November 1966). Generally, a limiting oxygen index of about 0.260 or greater is passable.

Dry Crease Recovery, total of angular degrees in warp (W) and filling (F) directions: ASTM D 1295- 60T.

Abbreviations OWB: On the weight of the bath used for padding, in percent. OWF: On the weight of the fabric, in percent. Wet pickup (in percent) multiplied by OWB/ 100% equals OWF (in percent). TMM: Trimethylol melamine, triyltriimino)-trimethanol. BEL: Burned entire length of fabric sample in vertical flame test.

(s-triazine-2,4,6-

Example 1 The compound P(O) (CH,OCONHCH,),

was prepared by adding 695 grams of methyl isocyanate to a suspension of 472 grams of tris-(hydroxymethyl)phosphine oxide in a mixture of 2,500 ml of henzene and 180 ml of pyridine at 60-70C. followed by 2 hours at reflux. The separated solid was crystallized from methyl alcohol to give 821 grams of product, m.p. 119-120C.; N found: 13.49 percent; theory 13.5 percent.

A quantity of 233 grams of the above compound was stirred at room temperature with 200 grams of 37 percent aqueous formaldehyde solution at a pH of 8-9 for 20 hours. The free formaldehyde content of the aqueous solution was reduced to 4.75 percent and there was produced the compound Example 2 Using the procedure described in Example 1, 627.5 grams of methyl isocyanate was added at 40-50C. to a-mixture of 1,275 grams of o (0.11.0 ,1 cmmcmcmorn,

2,000 ml of benzene and 100 grams of pyridine, the reaction mixture was refluxed for 5 hours and stripped of solvents under vacuo leaving a viscous liquid compound (11.43% N; theory 11.4%) having the formula (C l-1 0) P(O)(CH,N(CH CH,OCONHCH A mixture of 904 grams of the compound of the above formula and 169 grams of paraformaldehyde was stirred for 4 hours at 6070C. while maintaining a pH of 8-9 with 6N sodium hydroxide. A compound was produced having the formula Example 3 1,252 grams of phenyl chloroformate was added to a solution of 1,024 grams of in 2,000 ml of pyridine while cooling in a tap water bath. The product was poured into 1,200 ml of distilled water and the layers separated. The wash procedure was repeated several times and the residue was dried over MgSO, in 1:1 benzene/chloroform and stripped of solvents leaving 1478 grams of bis(carbonate ester) of the formula Ammonia gas was bubbled through a 2,000 ml pyridine solution containing 1,453 grams of the above bis(carbonate ester) at 20-30C. with cooling. When the exotherm subsided the mixture was poured into 2*liters of water and the lower layer was dried over anhydrous MgSO in 1:1 benzene/chloroform.Removal of the solvent and vacuum stripping at 90-100C. left a mixture of the desired intennediate compound and phenol which was separated by treatment with dilute sodium hydroxide (10 percent) solution and, extraction with chloroform. Removal of the chloroform from the dried extracts gave 137.5 grams of compound having the formula (CA-1,0),P(O)CH,N(CH,CH,OCONH,), which were treated with 184 grams of 37 percent aqueous formaldehyde solution at a pH 9.5-10 and a temperature of 6070C. for 14 hours, after which the free formaldehyde content was 5.75 percent. There was produced a compound of the formula 1f the procedure of Example 3 is repeated using as the phosphorus-containing alcohol starting material, there is produced the compound Example 4 Samples of the product of Example 3, phosphoruscontaining carbamate having the following formula /cmon (C IhOhP()0H N ClhCl-1=OCON\ cmolr were dissolved in a 2:1 dimethyl formamide/water mixture and either MgCl or an alkanolamine hydrochloride (Al-1C1) of the formula was added as catalyst. Concentrations of the reagent and catalyst are specified in the accompanying table.

Samples of sheeting fabric woven from all-cotton yarn in a plain weave, weighing 4.5 ounces per square yard, were padded in the treating solutions with the pressure of the squeeze rolls adjusted to give a wet pickup of about 80-100 percent. The padded samples of fabric were dried in a forced draft laboratory oven at approximately 66C., then cured. The conditions of the curing are specified in the accompanying table. The specimens of the fabric were washed for minutes at approximately 88C. in an aqueous solution of which 0.1 percent was sodium carbonate and 0.1 percent was a non-ionic detergent (Triton X-100, a mixture of closely related compounds having the formula where x has an average value of about 10). Finally, the fabric was neutralized in dilute acetic acid solution, rinsed in water, dried on a frame in a forced-draft oven and evaluated.

TABLE FOR EXAMPLE 4 Untreated Percent Rea em I AHCI 33.6 MgCl,

19.4 MgCl,

2 2 170C. for 5 minutes Example 5 Example 4 was repeated on cotton'sheeting samples pretreated with trimethylol melamine (TMM).

The pretreatment was carried out using the following method.

Samples of cotton fabric were padded with an 18 percent aqueous solution of trimethylol melamine containing 0.3% H 0 on a laboratory padder with the pressure of the squeeze rolls adjusted to give 100 percent wet pickup. The samples were dried to 20 percent moisture content, wrapped in a polyethylene sheet, and allowed to stand for 24 hours at room temperature, then washed and dried. By this procedure trimethylol melamine was insolubilized in essentially quantitative yield.

The results of the treatment of the trimethylol melamine pretreated samples (weight gain: 14.8%, N content: 4.5%) with the product of Example 3, phosphorus-containing carbamate having the following form'ula ClliOll cmou 1 5 are shown in the following table:

TABLE FOR EXAMPLE 5 are MgCl,

19.1 MgCl,

31.2 AJCI 18.4 AHCl Curing Weight Gain Percent Bound Phosphorus Percent Bound Nitrogen Limitlng Oxygen Index 0.29 0.24 Weight percent of treated fabric 25 Example 6 The product of example 1, phosphorus-containing carbamate having the following formula CHIOH was applied from a 31.0 percent aqueous solution containing 2 percent of the alkanol amine hydrochloride (AHCI) catalyst described in Example 4 to a fabric sample woven from twisted all-cotton yarn in a twill weave weighing 8 ounces per square yard. The application was carried out on a laboratory padder with the pressure of squeeze rolls adjusted to attain 86% wet pickup. The padded sample was dried, cured, washed and dried as described in Example 4. The so treated sample had a weight gain of 21.6 percent corresponding to 93 percent reaction yield.

The treated sample was after-treated with 15 percent aqueous trimethylol melamine solution containing 0.3% H 0, on a laboratory padder with the pressure of squeeze rolls adjusted to give 65 percent wet pickup. The sample was dried to 20-30 percent moisture content, steamed in a laboratory steamer for 8 minutes, washed and dried. The so treated sample had an additional 6.7 percent weight gain.

The results of the above applications before and after TMM treatment are shown in the accompanying table.

TABLE FOR EXAMPLE 6 no cniocors Before TMM After TMM Treatment Treatment Percent Bound Phosphorus 1.5 1.4 Percent Bound Nitrogen 1.8 4.3 Char Length in Vert. Flame Test BEL 5.5

Example 7 Aqueous solutions'containing a'mixture of the product of Example 1, phosphorus-containing carbamate having the following formula CHIC H 9 10 trimethylol melamine, and one of the acid catalysts deillustrative details are not to be construed as imposing scribed in Example 4 were applied to cotton twill fabric due limitations on the invention, samples using the method described in Example 4. The Wh t is laimed is; results of the treatment are shown in the accompanying 1 A h h m i i carbamate f the f table: 5 l

TABLE FOR EXAMPLE 7 (H) I CH2O a Untreated PercentRP Con- P R1 O EN taining eagent OWF 21.3 11,1 21.9 10 1 Percent TMM OWF 14.4 11.5 l4.8 Catalyst AHCl AHCl M cl, Percent Catalyst 2 2 1 wherein R an alkylene of one to five carbon atoms; gag St st SL R, is hydrogen, alkyl of one to five carbon atoms, or Cure Cure Cure CH OR R IS hydrogen or alkyl of one to five carbon Percent Weight atoms Gain 26.5 2L2 21.8 Percent P 1 0 0. 7 2. A compound of the formula Percent N 5.9 5.6 Char Length in Vertical Test Orig. 3.5 4.2 5.6 BEL (I? O /CH: IOL 4.2 4.2 5.6 L 4.2 5.2 5.2 P CHF'OJi-N 50L 3 s 5.7 8.5 CHZOH 3 Tensile Strength 1'' Strip w I76 162 I49 I83 Tear Strength ElmendorfF L2 L8 11 3. A compound of the formula Crease Recovery 25 w F Dry 238 227 243 I78 Flex Abr. w 2475 675 875 2425 O o CHZOH 3 minutes steaming followed by 5 minutes heat curing at l63C. U

P CHz-O-C-N It will be apparent that many modifications and varia- CHrOH a tions can be effected without departing from the scope of the novel concepts of the present invention, and the t a a 

2. A compound of the formula
 3. A compound of the formula 